The church is situated within Christ Church College, lying E of Tom Quad, which largely conceals it from the W. It is open to gardens on the N and E sides, with a 13thc Chapter House, a 16thc cloister, and college buildings enclosing it to S. The church is cruciform with a central tower. All four main arms have aisles, though the S transept lacks a W aisle where it abuts the cloister. The chancel has a square projecting E bay and four main bays; the 12thc nave had seven bays (reduced to four by the incursion of Tom Quad in the 16thc); the transepts have three bays, though the southernmost bay of the S transept is incorporated into the slype, and oversailed by what are now vergers’ offices. The elevation of the main vessels throughout is three-storey, the arcade and false triforium enclosed within a ‘giant order’; above is a clerestory with wall passage. There are traces of work before c.1150, but the present Romanesque building dates from the 1160s onwards. The chancel was built before the translation of St Frideswide’s relics to a chapel E of the N transept in 1180. The transepts and the nave were built soon after, to a grander, but not essentially modified, vision. In the 13thc the N chancel aisle was extended northwards to form a Lady Chapel, and an upper storey and spire added to the central tower. The Latin chapel was built N of the Lady chapel c.1338, to replace the reliquary chapel as a setting for St Frideswide’s shrine. The 12thc vault of the chancel was rebuilt c.1500, and those of the nave and transepts were replaced by timber ceilings in the 16thc, with modifications to the clerestories. There are quadripartite rib vaults in all aisles.

A legend recounts that there was an 8thc minster in possession of St Frideswide’s relics. A charter of Aethelred II mentions some reparation for a fire in the church in 1002, but the 11thc history of the monastic establishment is confusing and does not mention any fire. A priory of Augustinian canons was established under the indirect auspices of King Henry I sometime between 1111 and 1122, and the existing church was built from the 1160s. From 1525 the monastic buildings and the three W bays of the nave were destroyed to make room for Cardinal College, founded by Thomas Wolsey. As the college chapel, the truncated church building survived to become Christ Church Cathedral when the diocese of Oxford was established in 1546, with a Dean and Chapter. The cathedral was restored by George Gilbert Scott from 1871.

Restoration was particularly extensive in the E sanctuary bay, the S choir aisle, and at the S end of the south transept, with almost entirely new rooms above the slype.